Wild salmon spawn in restored Test carrier
Wind the clock back to October 2008 and Cain Bio's restoration team found themselves busy dismantling a fixed crest weir and live sewage pipe on a well known carrier of the River Test in Hampshire. Simon Cain had already been asked to look at the site some 10 years previously but his recommendation to demolish the weir wouldn't come to fruition untl the property changed hands in 2008.
The new owner, a keen fly fisherman with a leaning to wild salmon & trout conservation, asked Cain to draw up a restoration plan to remove the weir impoundment and re-route the suspended sewage pipe downstream and under the bed of the carrier.
With the impoundment gone, the now overwide but free-flowing channel was re-meandered using locally imported chalk, gravel and woody material from pollarded bankside Alders and Willow.
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| Salmon spawning habitat on CBE's carrier restoration on river Test |
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Freshly cut salmon redd - Photo: February 9th 2010 |
On completion, the heavily impacted river bed was jet sprayed to remove years of sediment build up prior to a re-dressing with locally imported gravel. Six extensive salmon-spawning sites were created along the 300m reach. Although turbid winter flows were fining down at least 9 salmon redds were clearly visible in the fast shallow riffles. These were mostly located on the new gravels in areas that were previously slow flowing and buried in 500mm sediment..
Man made impoundments of various kinds abound on rivers throughout the Uk. These structures are especially damaging on low gradient chalkstreams where a structure as basic as an unconsented scaffoldng board weir can back up flows causing sedimentation and habitat degradation for considerable distances upstream. If you own or are aware of such an impoundment, whether large or small and think there is an opportunity for similar habitat improvements do contact us. We would be pleased to arrange an advisory site visit.
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| Salmon redds on restored carrier. Photos: 09/02/10 |
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Large redd on new riffle due to multiple cutting. Photos: 09/02/10 |
This success story is but a drop in the ocean of degraded chalkstream habitats, but nevertheless an important case study in the quest to reverse a terminal decline in wild Test salmon stocks.
ENDS
NB: CBE's most recent habitat restoration on a heavily impounded stream is currently taking place on a 2km reach of the river Kennet. See news for details.